The father of jailed Iranian-American businessman Siamak Namazi has been detained, his family have said.

Security forces stopped Amu Baquer Namazi, 80, at Tehran’s Imam Khomeini airport on the night of February 22 as he returned from Dubai, where he had gone for a medical check-up and to visit his grandchildren.

According to IranWire sources, Revolutionary Guards Intelligence agents lured Namazi to go back to Iran by promising he would be able to visit his son for the first time since Siamak Namazi’s arrest in October 2015.

Instead of allowing him to see his jailed son, the security agents arrested Baquer Namazi at the airport, escorted him to his home, and then took him to Evin Prison after midnight.

“It is with utter shock and dismay and a heavy heart that we share the news of the arrest of Baquer Namazi, an 80-year old Iranian American, and father of Siamak Namazi,” his family told IranWire.

Authorities arrested Baquer Namazi’s son, Siamak Namazi, director of the strategic planning office of the Crescent Oil Company, in October 2015. Despite hopes that he would be released with other Iranian-American prisoners on January 16, he remains in prison. Namazi is well known for his work to improve business relations between the United States and Iran.

Baquer Namazi’s family say authorities have not given them or his lawyer any further information regarding the reason for his arrest or about his current condition.

“We are extremely concerned for his wellbeing given his serious heart condition which, along with other ailments, requires him to be administered with special medication every day. Additionally, Baquer, along the rest of his family, has been living under extremely emotional, stressful and traumatic conditions for the past few months since Siamak’s detention.”

Writing in the Wall Street Journal, prominent Iranian scholar and Middle East expert Haleh Esfandiari said security forces in Iran could be trying to force Siamak Namazi into making a confession by arresting his father, a retired civil servant.

“We call upon the authorities to immediately release Baquer Namazi, an innocent and fragile 80 year old man, and not to further jeopardize his health and wellbeing,” his family said. “We similarly call for the immediate release of Siamak Namazi.”

A high ranking former Iranian official who asked to remain anonymous told IranWire that Baquer Namazi’s arrest is part of a new Revolutionary Guards tactic. The Guards arrest Iranian-Americans with two objectives in mind. “They want to prevent Iranians in the diaspora from returning, because in their minds Iranians with dual nationalities can bring decadent western values into the country with them,” said the former official. “The other reason for the arrest of Iranian-Americans is that, as we saw in January [after the nuclear agreement was signed between Iran and the West], Iranian-Americans can be used as bargaining chips when it comes to negotiating with the United States.”